Difference between tanks from different countries is crew size and/or specialization (for example, soviet tanks early loss radioman, and crew size reduced from 5 to 4 men) and some equipment (for example, american tanks have Vertical Stabilizer from 6th tier when others from 7-8th tiers).
More specific parameters such armor, rate of fire, mobility depend on the specific tank.
German Panther have a great penetration but german VK 30.02(D) on
same tier have better mobility and diesel engine with rear transmission but 48mm less
French ARL 44 have a good armor and slow when AMX 50/100 poorly armored but have an incredible firepower and mobility.
Soviet IS-4 have thick rear and side armor and high penetration with moderate damage when IS-7 have poorly armored rear, high damage and moderate penetration.
Comparison of nations is meaningless. You need to compare specific tanks.